Judith Morales

Judith Morales
The National Museum of Natural Sciences · Evolutionary Ecology

PhD Biology

About

81
Publications
16,185
Reads
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2,786
Citations
Citations since 2016
19 Research Items
1174 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Introduction
I am interested in animal social behaviour in an evolutionary context. My current research focuses on questions such as how flexible decision rules are in social interactions and how this flexibility is shaped by ontogenetic effects and environmental changes. Please, visit the Social Evolution Unit website: http://judith-morales.com
Additional affiliations
April 2016 - present
The National Museum of Natural Sciences
Position
  • Fellow
January 2011 - April 2015
The National Museum of Natural Sciences
Position
  • PostDoc Position
July 2008 - December 2010
University of Vigo
Position
  • PostDoc Position

Publications

Publications (81)
Article
Full-text available
Blue-green colours in avian eggs have been proposed as post-mating signals of female phenotypic quality to their mates. Egg colour may not only indicate female value, but also the quality of the eggs themselves and of resulting offspring. To date, there has been no demonstration of an association between egg colour and egg or offspring immune quali...
Article
Full-text available
In 1950, Tinbergen described the elicitation of offspring begging by the red spot on the bill of parent gulls, and this became a model system for behavioural studies. Current knowledge on colour traits suggests they can act as sexual signals revealing individual quality. However, sexual signals have never been studied simultaneously in relationship...
Article
Full-text available
Theory predicts that the trade-off between ornamentation and fecundity limits female attractiveness. However, there is little evidence on this theoretical trade-off and its proximate background. Our aim was to study whether pigment availability modulates this potential relationship in blue-footed booby females. We supplemented females with dietary...
Article
Full-text available
Although the role of animal signals in the resolution of family conflicts has been thoroughly studied, it has been typically analysed in isolated two-player interactions. For instance, parents are usually considered as the sole receivers of offspring begging signals or mates the receivers of sexual displays. However, this view does not wholly encom...
Article
Full-text available
In this essay, I propose the hypothesis that biliverdin pigment plays an antioxidant role in the avian eggshell. Due to its ability to scavenge free radical species and to reduce mutation, biliverdin potentially counteracts the oxidative action of pathogens that penetrate the eggshell and/or protects the shell membrane from oxidation, thus promotin...
Article
Full-text available
In many vertebrates, the enzymatic oxidation of dietary yellow carotenoids generates red keto‐carotenoids giving color to ornaments. The oxidase CYP2J19 is here a key effector. Its purported intracellular location suggests a shared biochemical pathway between trait expression and cell functioning. This might guarantee the reliability of red colorat...
Preprint
In many species, offspring display conspicuous adult-like colouration already early in life, even though they might be very vulnerable to predation at this stage. Yet, the signalling function of adult-like traits in nestlings has been little explored to date. Here, we investigated whether the yellow breast plumage of blue tit (Cyanistes caeruleus)...
Article
Full-text available
Avian feathers need to be replaced periodically to fulfill their functions, with natural, social, and sexual selection presumably driving the evolution of molting strategies. In temperate birds, a common pattern is to molt feathers immediately after the breeding season, the pre-basic molt. However, some species undergo another molt in winter-spring...
Article
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In bi-parental species, reproduction is not only a crucial life-history stage where individuals must take fitness-related decisions, but these decisions also need to be adjusted to the behavioural strategies of other individuals. Hence, communication is required, which could be facilitated by informative signals. Yet, these signalling traits might...
Article
Full-text available
Parents allocate resources to offspring to increase their survival and to maximize their own fitness, while this investment implies costs to their condition and future reproduction. Parents are hence expected to optimally allocate their resources. They should invest equally in all their offspring under good conditions, but when parental capacity is...
Preprint
Full-text available
In bi-parental species, reproduction is not only a crucial life-history stage where individuals must take fitness-relevant decisions, but these decisions also need to be adjusted to the behavioural strategies of a partner. Hence, communication is required, which could be facilitated by condition-dependent signals of parental quality. Yet, these tra...
Article
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During egg laying, females face a trade‐off between self‐maintenance and investment into current reproduction, since providing eggs with resources is energetically demanding, in particular if females lay one egg per day. However, the costs of egg laying not only relate to energetic requirements, but also depend on the availability of specific resou...
Poster
Full-text available
During egg laying, female birds face a trade-off between self-maintenance and investment into current reproduction. Providing eggs with resources is energetically demanding, since in most species females lay one egg per day. However, the costs of egg laying not only relate to energetic requirements, but also depend on the availability of specific r...
Article
Heterozygosity affects mate selection and can modulate interactions among family members and their fitness-related decisions. We studied whether nestling heterozygosity affected parent–offspring interactions and sib–sib competition in the Blue Tit (Cyanistes caeruleus) while controlling for the degree of relatedness among nestlings. Demanding envir...
Article
The offspring of many animals are conspicuous during parental dependence, despite juveniles generally suffering from high predation risk. However, to date, it is unclear whether offspring structural ornaments play a role in intrafamily communication. This is the case of conspicuous plumage in young birds, which is worn unchanged during a long perio...
Article
Factors affecting the evolution of plumage conspicuousness in females are nowadays the focus of debate, and here we explore the possibility that the conspicuousness of female plumage and male participation in nest building are associated in birds. We hypothesize that males that participate in nest building will gain higher fecundity from high-quali...
Article
Full-text available
It is known that heterozygosity affects mate selection in various taxa. But also beyond mating, in species with parental care, heterozygosity can modulate interactions among family members and their fitness-related decisions. However, to date, this question remains little explored. Here, we studied whether nestling heterozygosity was related to par...
Poster
Full-text available
Mothers can influence offspring phenotype through their allocation into eggs, which may have profound consequences for offspring ontogeny and survival. However, it is little known how these early maternal effects modulate the expression of signals of quality in their offspring. This is striking, given that in many animals offspring express ornament...
Article
Full-text available
The resolution of family conflicts over parental care involves elaborate behavioral interactions where signals and information exchange play a central role. Usually, the focus is on offspring begging and adult signals and their effect on parental provisioning. Yet, despite offspring of many animal species display structural ornaments during parenta...
Data
Model selection for female behavioral traits (Table A1)
Data
Model selection for male behavioral traits (Table A2)
Article
Full-text available
Predation risk is an important environmental factor for animal populations, expected to trigger maternal effects to prepare offspring for living in an environment with predators. Yet, evidence of adaptive anticipatory maternal effects in wild animals is still weak. Here, we explored this question in a wild colony of yellow-legged gulls, Larus micha...
Data
Summary information on studies of the relationship between clutch size and nest size in different species of birds.
Article
Full-text available
Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose...
Article
Full-text available
There is increasing evidence that sexual selection operates in females and not only in males. However, the function of female signals in intrasexual competition has been little studied in species with conventional sex roles. In the Iberian populations of the pied flycatcher (Ficedula hypoleuca), some females express a white forehead patch, a trait...
Article
Full-text available
Micronutrients are essential for normal metabolic processes during early development. Concretely, it has been suggested that diet-derived carotenoids can play a key role in physiological functions due to their antioxidant and immunostimulant properties. However, their role as antioxidants remains controversial. Additionally, it is also unclear whet...
Article
Full-text available
Among the cellular pathways conferring protection against oxidative stress, a key role is played by heat-shock proteins, especially HSP70. It has been proposed that blue egg colouration in certain birds, which is related to the deposition of the pigment biliverdin, should be related to basic antioxidant processes in the laying female given the stro...
Article
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Birds have been used as bioindicators of pollution, such as toxic metals. Levels of pollutants in eggs are especially interesting, as developing birds are more sensitive to detrimental effects of pollutants than adults. Only very few studies have monitored intraspecific, large-scale variation in metal pollution across a species' breeding range. We...
Article
Full-text available
Besides the direct functionality of nests driven by natural selection, accumulating evidence shows that nest building behaviors and nests may also evolve under sexual selection. Empirical research on the potential role of nests or nest features as sexual signals, however, is comparatively scarce for avian species in which the female is the only sex...
Article
Full-text available
The expression and impact of maternal effects may vary greatly between populations and environments. However, little is known about large‐scale geographical patterns of variation in maternal deposition to eggs. In birds, as in other oviparous animals, the outermost maternal component of an egg is the shell, which protects the embryo, provides essen...
Article
Ageing is a crucial requisite for any analysis of growth and development. However, ageing by regular nest visits around hatching is time-consuming. Thus, species-specific developmental patterns are used to estimate nestling age at infrequent nest visits during the nestling period. Unfortunately, comprehensive species-specific data on the timing of...
Article
Full-text available
In evolutionary biology, whether parents should enhance or reduce parental care according to mate ornamentation is a subject of great debate. However, the evolution of female ornaments can shed light on this question. In theory, female ornamentation should be traded off against fecundity and thus cannot be wholly informative to males without a dire...
Article
Full-text available
Some avian species incorporate aromatic plants to their nests. The "nest protection hypothesis", which posits that volatile secondary compounds contained in these plants may have antiparasite properties, has not received full support. All previous tests of this hypothesis have only considered effects on nest-dwelling ectoparasites, but not on blood...
Article
Full-text available
The evolution of begging display may be influenced by gene–environment interaction, through the mechanisms that adjust begging behaviour to environmental conditions of offspring, including intensity of sibling competition within broods. We decomposed the complex begging display of yellow-legged gull, Larus michahellis, chicks into two different fun...
Article
Full-text available
The colour fading in eggs of the Pied Flycatcher was studied in Spain. Egg colour for >400 eggs was estimated at the moment of oviposition, at the onset of incubation, and at the end of incubation. Results, obtained using a spectrophotometer, showed that egg colours tended to fade significantly during the study period. For unhatched eggs over lon-g...
Article
Full-text available
Why do animals not grow at their maximal rates? It has been recently proposed that fast growth leads to the accumulation of cellular damages due to oxidative stress, influencing subsequent performances and life span. Therefore, the trade-off between fast growth and oxidative stress may potentially function as an important constraint in the evolutio...
Article
Full-text available
Conditions experienced during early life can influence the development of an organism and several physiological traits, even in adulthood. An important factor is the level of oxidative stress experienced during early life. In birds, extra-genomic egg substances, such as the testosterone hormone, may exert a widespread influence over the offspring p...
Article
Full-text available
Avian eggshell color is remarkably variable among and within species and its possible function has long been controversial. Female birds use biliverdin pigment to color their eggs blue and green. Although evidence is accumulating that blue-green eggshell coloration is costly to produce, the exact mechanisms underlying its expression are little stud...
Article
Full-text available
Parasites are undoubtedly a biotic factor that produces stress. Heat shock proteins (HSPs) are important molecules buffering cellular damage under adverse conditions. During the breeding season, blue tit Cyanistes caeruleus (L.) adults are affected by blood parasites, nest-dwelling parasites and biting flies, potentially affecting their HSP-mediate...
Article
Full-text available
Avian blue-green eggshell coloration has been proposed as a female signal of genetic or phenotypic quality to males. However, little is known about the relative importance of additive genetic and environmental effects as sources of eggshell colour variation in natural populations. Using 5 years of data and animal models, we explored these effects i...
Article
Full-text available
Glucocorticoids promote the mobilization of energy stores and they may facilitate the expression of energetically expensive functions. Early arrival on the breeding grounds in migratory species and territorial competition are energetically demanding activities that may be supported by elevated baseline glucocorticoid levels. Here, we evaluated the...
Article
Full-text available
Offspring solicit food to their parents by begging displays, which are important in the parent–offspring communication. Most theoretical approximations on this behavior have centered on the view of begging as an honest signal of need or as a form of scramble competition for resources. In both signaling models, costly begging is necessary to stabili...
Article
Full-text available
When both parents provide offspring care, equal sharing of costly parental duties may enhance reproductive success. This is crucial for longlived species, where increased parental effort in current reproduction profoundly affects future reproduction. Indication of reproductive value or willingness to invest in reproduction may promote matching resp...
Article
Full-text available
Oxidative stress has recently been suggested to play an important role in life-history evolution, but little is known about natural variation and heritability of this physiological trait. Here, we explore phenotypic variation in resistance to oxidative stress of cross-fostered yellow-legged gull (Larus cachinnans) chicks. Resistance to oxidative st...
Article
Full-text available
While avian chronic haemoparasite infections induce reproductive costs, infection has not previously been shown to affect survival. Here, we experimentally reduced, through medication, the intensity of infection by Haemoproteus parasites in wild-breeding female blue tits Cyanistes caeruleus. However, this treatment did not reduce the intensity of i...
Article
For sexual selection to operate in monogamous species, males of poor quality in some factor like age, ornamentation, condition or aggressiveness, should lose paternity compared with higher quality males. We tested this idea in an Iberian population of pied flycatchers (Ficedula hypoleuca). Microsatellite analysis of 67 broods revealed moderate leve...
Article
Full-text available
Laying date is a key factor in avian reproductive ecology. Benefits of early breeding are important in terms of reproductive output. Costs are mainly associated to weather adversities at early stages of the breeding season. As males arrive earlier than females, they may face these weather adversities more frequently and therefore suffer higher cost...
Article
Full-text available
Carotenoids are molecules that birds are not able to synthesize and therefore, must be acquired through their diet. These pigments, besides their function of giving birds red and yellow colouration when deposited in feathers, seem to act as immune-stimulators and antioxidants in the organism. Hence, only the healthiest individuals would be able to...
Article
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Capsule Some males brought building materials to nests and females who were paired with such males laid heavier clutches.
Article
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Mechanisms affecting patterns of vector distribution among host individuals may influence the population and evolutionary dynamics of vectors, hosts and the parasites transmitted. We studied the role of different factors affecting the species composition and abundance of Culicoides found in nests of the blue tit (Cyanistes caeruleus). We identified...
Article
Full-text available
En este trabajo exploramos dos de las varias hipótesis que se han propuesto para intentar explicar la variabilidad intraespecífica en el tamaño del nido. La hipótesis de la “termorregulación” propone que el tamaño del nido se optimizaría para mantener la temperatura de los huevos y minimizar las fluctuaciones de temperatura. Recientemente, se ha su...
Article
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Overlapping moult and reproduction might be crucial for long-distance migratory birds, which are time-constrained to complete these energy-demanding functions before the onset of migration. However, proximate factors modulating the potential trade-off between moult and breeding, such as haemoparasite infection and stress, have not been studied in w...
Article
Full-text available
Although evidence is accumulating on the adaptive function of female ornamentation, very little is known about maternal allocation decisions involving sexual signaling and other reproductive functions. Blue egg coloration has been suggested as a sexually selected signal of female quality to males, and some recent studies are in accordance with this...
Article
Sex differences in immune function are relatively well studied in vertebrate animals, although the patterns are not always clear in birds. The study of immune responses in nestlings of wild bird populations may constitute an appropriate way to investigate inherent intersexual differences while controlling for environmental conditions such as parasi...
Article
Full-text available
We have aimed at detecting prelaying maternal effects on nestling antibody defences and growth through experimental food supplementation of female pied flycatchers Ficedula hypoleuca and subsequent exchange of whole clutches with control nests. The levels of immunoglobulins and the mass and size of chicks at 12 days of age were ascertained. This is...
Article
Full-text available
Nest building effort has received scant attention in the literature although it may involve costs which can be detected as physiological stress. We prolonged nest construction effort in a population of Spanish Pied Flycatchers by removing nests from nest-boxes and forcing females to build a second nest. In comparison with control nests, the experim...
Article
Full-text available
Compared to non-flying nest-dwelling ectoparasites, the biology of most species of flying ectoparasites and its potential impact on avian hosts is poorly known and rarely, if ever, reported. In this study we explore for the first time the factors that may affect biting midge (Diptera: Ceratopogonidae) and black fly (Diptera: Simuliidae) abundances...
Article
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[KEYWORDS: birds; biting midges; blackflies; blood parasite-insect vector-vertebrate host relationships; Ceratopogonidae; Culicoides; distance to water sources; insecticide treatment; sampling methods; Simuliidae]
Article
The hypothalamic-pituitary-adrenal (HPA) axis of birds induces the secretion of corticosterone (CORT) as a response to different ecological variables. In this study we tested experimentally if manipulations of brood size or ectoparasitism led to subsequent differences in the concentration of excreted CORT metabolites of adult and nestling blue tits...
Article
Full-text available
Multiple invasions (MIs) or infections, i.e. those by more than 1 parasite in the same erythrocyte, could be the result of parasite density or, alternatively, to parasite-related factors or host-related factors. According to the last possibility, to our knowledge, only 3 laboratory studies of malaria have found an increase in the occurrence of MIs...
Article
Research on the costs of nest reuse is central to understanding the population ecology and evolution of cavity-nesting birds. We explored the consequences of nest reuse by offering blue tits three types of nestboxes in which to breed: nestboxes with an old nest (O), empty nestboxes (E) and nestboxes with an old nest fumigated with insecticide (F)....
Article
Full-text available
We explore the relationship between general eggshell colour (background and spots) and proportion of surface covered by spots on the eggs of blue tits Cyanistes caeruleus and several variables reflecting female health and condition. Females laying more spotted eggs showed a poorer body condition, higher cellular concentration of the stress protein...